The effect of synchronization errors on the performance of telescope arrays for optical deep space communications

Evolving optical deep space communication network architecture requires incremental growth in the total aperture. On the other hand, the cost of a large aperture telescope grows exponentially as a function of its diameter, therefore telescope array architecture could provide a cost effective scalable growth for an evolving optical deep space network. However, the total aperture size and the corresponding breakdown into smaller individual telescope segments poses some system architecture impact in terms of site selection of the entire network, and the number of telescopes that fall within the footprint from the space-to-Earth at various distances, e.g., Moon, Mars, etc. In this paper, the effect of synchronization on the performance of the telescope arrays is analyzed. An adaptive method based on Kalman filtering is developed and used to synchronize different telescope signals in a telescope array with PPM modulation and direct detection. It is shown that the degradation in combined signal due to synchronization error can be reduced to a small value so that it places only a minor limitation on the number of telescopes in a telescope array.